Is it true driving in OD is harder on the tranny when travelling under 55mph?

I dont see how... OD makes everything spin slower so less wear one would think. If it was harmful to the trans life, I highly doubt Ford would let the stock program shift the trans into OD at under 55.

Depending on the vehicle, the transmission may shift into OD as low as 32 mph. I turn off O/D while in the city to reduce constant 3-4 and 4-3 shifting.

Since I have a first gen, I don't have electronic OD, so I can either shift into D or OD.

it can be i use mine in the wet you get a lot better engine breaking stops it from shifting into 5th

it's bad for the tranny to keep hunting in and out of OD while driving at city speeds. The more it shifts the more heat it creates and the more wear on the friction material. By disengaging OD you keep it from shifting excessivey which can make your tranny last longer.

i have a gen 1, i drive in OD all the time....is that bad?

Originally posted by bdogg23
i have a gen 1, i drive in OD all the time....is that bad? I used to also. I've got about 85k miles driven in OD until one day I was driving with a friend and he reached his hand over and shifted it into D. He said it's harder on the transmission when keeping it in overdrive under 55. I've used drive ever since and don't see much of a difference, but it's better being safe then sorry.

your tranny actually works harder in od if the speed isnt above 55. the gas mileage suffers also. if you were in 4th @ 45 instead of 5th the rpm's would carry the truck easier, but with the lower rpm's the truck is forced to either pull the load under more strain from the engine (which is being given more gas to compensate because it is trying to pull the truck up from a lower rpm) or downshift and then upshift several times @ 45 throughout your trip which causes excessive wear and heat.

The Overdrive Clutch B is engaged in all Drive gears. No, this isn't the clutch that gives you overdrive. I believe this reinforces the Overdrive One Way Clutch. In OD this clutch is always off. Evidently the transmission can't sync the OD clutch and band (this would lock up the drive). So using Drive should reduce wear on the one way clutch. Historically the OD section has been a little weak in the first gen. I've never noticed much change in gas mileage on trips when in just Drive.

I always drive around town in D and then when I get on the freeway I will put it in OD. When I am getting off the freeway I will downshift to D around 55 to get some engine breaking.

I ran two tanks of gas through my Explorer where I left OD disabled until I was above 55 MPH. Those two tanks of gas I averaged 1 1/2 MPG less than the ones before and after. Gas was bought at the same station each time. My daily commute consisted of about 10 miles of city streets to about 50 MPH and then 20 miles of freeway (sometimes stop and go when traffic was very heavy). That was enough to convince me to leave mine on. I have 104K on my transmission now.

A good rule of thumb to go with is to keep it in D on hills, or if the transmission is shifting a lot to keep up with speed changes.

I drive in D in the city and keep OD for Highway speeds. Transmission seems to like that better as does gas mileage.:)